1. Technical Field
The present invention relates to a line head and an image forming device using the line head that simplify wiring connections where light sources are arranged two-dimensionally to be connected to a drive circuit, and that rationally perform image formation.
2. Related Art
A toner image formation section of an electrophotographic system generally includes a photoconductor drum as an image carrier having a photoconductive layer on its outer circumferential surface, a charging section for evenly charging the outer circumferential surface of the photoconductor drum, an exposure section for selectively exposing the outer circumferential surface thus evenly charged by the charging section to form an electrostatic latent image, and a development section for providing toner as a development agent to the electrostatic latent image thus formed by the exposure section to make the electrostatic latent image a visible image (a toner image).
An exposure section is known that uses a line head provided with a light emitter array. Light emitting elements such as LEDs or organic EL elements are provided in the light emitter array. The output light from the light emitting elements is provided to the photoconductor drum through an imaging lens. A lens with positive optical power (e.g., a SELFOC™ lens) and a lens with negative optical power (e.g., a microlens) may be used as the imaging lens. For example, JP-A-2004-209777 describes a case in which the output light of light emitting elements arranged two-dimensionally in a light emitter array is provided to a photoconductor drum through an imaging lens with positive optical power to form a latent image. The light emitting elements are controlled by a drive circuit.
FIG. 8 is a block diagram illustrating the drive circuit of JP-A-2004-209777. In FIG. 8, main controller 80 is connected to a control section 70 of a line head. A plurality of light emitting elements 61 for which organic EL elements are used is arranged in an axial direction (the X or main-scanning direction) of the photoconductor drum and a rotational direction (the Y or sub-scanning direction) of the photoconductor drum. A plurality of rows of the light emitting elements 61 is arranged in the Y direction for the purpose of improvement of resolution and so on. The light emitting elements 61 are connected to a drive circuit 76. The image data formed by the main controller 80 is transmitted to the control section 70, and temporarily stored in a memory 77. A control circuit 75 retrieves the image data stored in the memory 77, and forms a drive signal to supply each of the light emitting elements 61 with the drive signal via the drive circuit 76.
When the light emitting elements are arranged two-dimensionally, the drive circuit must be operated after executing reordering of the image data so as to be reversed in the axial and rotational directions of the photoconductor drum in a configuration using microlenses with negative optical power as the imaging lenses. However, imaging lenses with positive optical power are used in the line head of JP-A-2004-209777. Therefore, if the technology of JP-A-2004-209777 is used as it is, there is a problem in that a latent image different from the original image in the rotational direction of the photoconductor drum is formed, and the image quality is therefore degraded.
Further, in a line head having a number of light emitting elements arranged in the X and Y directions of the substrate as shown in FIG. 8, since the wiring connections between the light emitting elements and the drive circuit is made in a narrow space, there is a problem in that making the wiring connections is troublesome. In particular, in a configuration using microlenses with negative optical power as the imaging lenses, since reversal of image data as described above is required, the wiring connections between the light emitting elements and the drive circuit is further complicated.